1. Field of the Inventions
The present inventions relate to a water cooling device for an outboard motor, and more particularly, outboard motors with cooling water jackets formed on an oil pan for an internal combustion engine and a cooling water passage for connecting the cooling water jacket with the internal combustion engine.
2. Description of the Related Art
One type of outboard motor is disclosed in Japanese Patent Documents JP-A-Hei9-189224 and JP-A-2000-62694. In each of these Patent Documents, the outboard motors have a case supported by a hull of a watercraft, an internal combustion engine supported on the upper end of the case, an oil pan formed in the case for storing lubricating oil for the internal combustion engine, and a cooling water jacket formed integrally with the oil pan. A cooling water passage connects the cooling water jacket with the internal combustion engine.
When the internal combustion engine is driven, the lubricating oil in the oil pan is supplied to the internal combustion engine to lubricate the parts of the internal combustion engine. The internal combustion engine can be thereby, continuously driven smoothly.
When the internal combustion engine is driven, cooling water is supplied into the cooling water jacket of the oil pan and the cooling water is supplied to the internal combustion engine. Then, the lubricating oil in the oil pan is cooled by the cooling water, thereby preventing deterioration of the lubricating oil, and the internal combustion engine is also cooled to prevent a temperature rise thereof.
In the above-noted outboard motor designs, a large amount of the lubricating oil stored in the oil pan is supplied to the internal combustion engine when the internal combustion engine is being driven. Thus, the level of the lubricating oil in the oil pan is near the bottom of the oil pan. As a result, less lubricating oil remains in the upper part of the oil pan, and thus the upper part of the oil pan can remain empty. The oil pan is cooled along its entire length in the vertical direction by at least either the cooling water jacket or the cooling water passage.